1. Field of the Invention
The present invention relates to improvements in a dental treatment apparatus with a root canal length measurement function, being capable of treating root canals while measuring the lengths thereof by using a cutting tool also as an electrode for root canal length measurement.
2. Description of the Prior Art
Apparatuses being capable of treating root canals while measuring the lengths thereof by using a cutting tool, such as a file or a reamer, also as an electrode for root canal length measurement are known. (Refer to Japanese Utility Model Publication No. 57-3303 and Japanese Laid-open Patent Application No. 5-64643, for example.) The handpiece used in this case is connected to the main control unit via a single tube in which control lead wires and other wires and pipes, such as a water supply pipe when required, are incorporated. This tube forms a cause for worsening the operability of the handpiece. Furthermore, since in a conventional apparatus, a root canal length measurement circuit and an indication section for showing the measurement results are installed in the main control unit which is separate from the handpiece, the operator of the apparatus is required to turn his eyes from an affected part to the indication section each time confirming the indicated data.
In the above-mentioned conventional example, the lead wires for the root canal length measurement circuit are directly connected from the main control unit to the cutting tool of the handpiece, separately from the above-mentioned tube. This structure worsens the operability of the handpiece, and requires to externally connect the lead wires of the measurement circuit at each treatment, making operation troublesome.